Abdullah bin al-Zubair appointed himself caliph. The people paid him homage. Some people liked him. Some disliked the Umayyads.
Mukhtar knew that Abdullah bin al-Zubair was ambitious. Anyhow, he paid him homage because he hated the Umayyads.
Yazeed bin Mu'awiyah had killed Imam Husayn and captured his family. So, the people of al-Madina al-Munawwara, the majority of the Prophet's companions were with them, revolted against him.
Muslim bin Akkaba, whom the people called Mujrim bin Akkaba, headed the Shamian Army. He attacked al-Madina al-Munawwara and the Prophet's Holy Shrine. He committed massacre. The number of the killed was more than fifteen thousand people. He violated the women. Then he put them in markets for sale.
After that massacre, Yazeed's Army headed for Makkah to occupy it.